m_days.c

#include <stdio.h>

#define NUM_OF_ELEMENTS(array) (sizeof(array)/sizeof(array[0]))

main() {

    int ys[] = {2011, 2012, 2100, 2400};
    int i = 0, m = 0;

    for(i = 0; i < NUM_OF_ELEMENTS(ys); i++) {

        int y = ys[i];
        printf("year: %d\n", y);

        for(m = 1; m <= 12; m++) {

            int m_days = 30 + (m+(m>=8))%2 - 2*(m==2) + (m==2 && (!(y%4) && !!(y%100) || !(y%400)));
            printf("%d\n", m_days);

        }

        printf("\n");
    }
}